[clang-format] Add support for DanglingParenthesis

docs/ClangFormatStyleOptions.rst

@@ -950,6 +950,20 @@ the configuration (without a prefix: ``Auto``).
       return 0;
     }
 
+**DanglingParenthesis** (``bool``)
+  If there is a break after the opening parenthesis, also break before the closing parenthesis
+
+  .. code-block:: c++
+
+    true:
+    someLongFunction(
+          argument1, argument2
+    );
+
+    false:
+    someLongFunction(
+          argument1, argument2);
+
 **ConstructorInitializerIndentWidth** (``unsigned``)
   The number of characters to use for indentation of constructor
   initializer lists.

include/clang/Format/Format.h

@@ -778,6 +778,20 @@ struct FormatStyle {
   /// \endcode
   bool ConstructorInitializerAllOnOneLineOrOnePerLine;
 
+  /// \brief If there is a break after the opening parenthesis, also break
+  /// before the closing parenthesis
+  /// \code
+  ///   true:
+  ///   someLongFunction(
+  ///       argument1, argument2
+  ///   );
+  ///
+  ///   false:
+  ///   someLongFunction(
+  ///       argument1, argument2);
+  /// \endcode
+  bool DanglingParenthesis;
+
   /// \brief The number of characters to use for indentation of constructor
   /// initializer lists.
   unsigned ConstructorInitializerIndentWidth;

lib/Format/ContinuationIndenter.cpp

@@ -143,6 +143,9 @@ bool ContinuationIndenter::canBreak(const LineState &State) {
       State.Stack.back().NoLineBreakInOperand)
     return false;
 
+  if(Current.is(tok::r_paren) && !State.Stack.back().BreakBeforeClosingParen)
+    return false;
+
   return !State.Stack.back().NoLineBreak;
 }
 
@@ -154,6 +157,8 @@ bool ContinuationIndenter::mustBreak(const LineState &State) {
   if (State.Stack.back().BreakBeforeClosingBrace &&
       Current.closesBlockOrBlockTypeList(Style))
     return true;
+  if(State.Stack.back().BreakBeforeClosingParen && Current.is(tok::r_paren))
+    return true;
   if (Previous.is(tok::semi) && State.LineContainsContinuedForLoopSection)
     return true;
   if ((startsNextParameter(Current, Style) || Previous.is(tok::semi) ||
@@ -629,6 +634,9 @@ unsigned ContinuationIndenter::addTokenOnNewLine(LineState &State,
         PreviousNonComment->opensScope())))
     State.Stack.back().BreakBeforeClosingBrace = true;
 
+  if (PreviousNonComment && PreviousNonComment->is(tok::l_paren))
+    State.Stack.back().BreakBeforeClosingParen = Style.DanglingParenthesis;
+
   if (State.Stack.back().AvoidBinPacking) {
     // If we are breaking after '(', '{', '<', this is not bin packing
     // unless AllowAllParametersOfDeclarationOnNextLine is false or this is a
@@ -674,6 +682,9 @@ unsigned ContinuationIndenter::getNewLineColumn(const LineState &State) {
       return State.Stack[State.Stack.size() - 2].LastSpace;
     return State.FirstIndent;
   }
+  if (Style.DanglingParenthesis && Current.is(tok::r_paren) && State.Stack.size() > 1) {
+    return State.Stack[State.Stack.size() - 2].LastSpace;
+  }
   if (NextNonComment->is(TT_TemplateString) && NextNonComment->closesScope())
     return State.Stack[State.Stack.size() - 2].LastSpace;
   if (Current.is(tok::identifier) && Current.Next &&

lib/Format/ContinuationIndenter.h

@@ -149,12 +149,13 @@ struct ParenState {
   ParenState(unsigned Indent, unsigned LastSpace, bool AvoidBinPacking,
              bool NoLineBreak)
       : Indent(Indent), LastSpace(LastSpace), NestedBlockIndent(Indent),
-        BreakBeforeClosingBrace(false), AvoidBinPacking(AvoidBinPacking),
-        BreakBeforeParameter(false), NoLineBreak(NoLineBreak),
-        NoLineBreakInOperand(false), LastOperatorWrapped(true),
-        ContainsLineBreak(false), ContainsUnwrappedBuilder(false),
-        AlignColons(true), ObjCSelectorNameFound(false),
-        HasMultipleNestedBlocks(false), NestedBlockInlined(false) {}
+        BreakBeforeClosingBrace(false), BreakBeforeClosingParen(false),
+        AvoidBinPacking(AvoidBinPacking), BreakBeforeParameter(false),
+        NoLineBreak(NoLineBreak), NoLineBreakInOperand(false),
+        LastOperatorWrapped(true), ContainsLineBreak(false),
+        ContainsUnwrappedBuilder(false), AlignColons(true),
+        ObjCSelectorNameFound(false), HasMultipleNestedBlocks(false),
+        NestedBlockInlined(false) {}
 
   /// \brief The position to which a specific parenthesis level needs to be
   /// indented.
@@ -210,6 +211,13 @@ struct ParenState {
   /// was a newline after the beginning left brace.
   bool BreakBeforeClosingBrace : 1;
 
+  /// \brief Whether a newline needs to be inserted before the block's closing
+  /// paren.
+  ///
+  /// We only want to insert a newline before the closing paren if there also
+  /// was a newline after the beginning left paren.
+  bool BreakBeforeClosingParen : 1;
+
   /// \brief Avoid bin packing, i.e. multiple parameters/elements on multiple
   /// lines, in this context.
   bool AvoidBinPacking : 1;
@@ -275,6 +283,8 @@ struct ParenState {
       return FirstLessLess < Other.FirstLessLess;
     if (BreakBeforeClosingBrace != Other.BreakBeforeClosingBrace)
       return BreakBeforeClosingBrace;
+    if (BreakBeforeClosingParen != Other.BreakBeforeClosingParen)
+      return BreakBeforeClosingParen;
     if (QuestionColumn != Other.QuestionColumn)
       return QuestionColumn < Other.QuestionColumn;
     if (AvoidBinPacking != Other.AvoidBinPacking)

lib/Format/Format.cpp

@@ -315,6 +315,7 @@ template <> struct MappingTraits<FormatStyle> {
                    Style.BreakBeforeInheritanceComma);
     IO.mapOptional("ConstructorInitializerAllOnOneLineOrOnePerLine",
                    Style.ConstructorInitializerAllOnOneLineOrOnePerLine);
+    IO.mapOptional("DanglingParenthesis", Style.DanglingParenthesis);
     IO.mapOptional("ConstructorInitializerIndentWidth",
                    Style.ConstructorInitializerIndentWidth);
     IO.mapOptional("ContinuationIndentWidth", Style.ContinuationIndentWidth);
@@ -541,6 +542,7 @@ FormatStyle getLLVMStyle() {
   LLVMStyle.ColumnLimit = 80;
   LLVMStyle.CommentPragmas = "^ IWYU pragma:";
   LLVMStyle.ConstructorInitializerAllOnOneLineOrOnePerLine = false;
+  LLVMStyle.DanglingParenthesis = false;
   LLVMStyle.ConstructorInitializerIndentWidth = 4;
   LLVMStyle.ContinuationIndentWidth = 4;
   LLVMStyle.Cpp11BracedListStyle = true;
@@ -606,6 +608,7 @@ FormatStyle getGoogleStyle(FormatStyle::LanguageKind Language) {
   GoogleStyle.AlwaysBreakBeforeMultilineStrings = true;
   GoogleStyle.AlwaysBreakTemplateDeclarations = true;
   GoogleStyle.ConstructorInitializerAllOnOneLineOrOnePerLine = true;
+  GoogleStyle.DanglingParenthesis = false;
   GoogleStyle.DerivePointerAlignment = true;
   GoogleStyle.IncludeCategories = {{"^<.*\\.h>", 1}, {"^<.*", 2}, {".*", 3}};
   GoogleStyle.IncludeIsMainRegex = "([-_](test|unittest))?$";

lib/Format/TokenAnnotator.cpp

@@ -2652,7 +2652,10 @@ bool TokenAnnotator::canBreakBefore(const AnnotatedLine &Line,
   if (Right.is(TT_ImplicitStringLiteral))
     return false;
 
-  if (Right.is(tok::r_paren) || Right.is(TT_TemplateCloser))
+  if (Right.is(tok::r_paren)) {
+    return Style.DanglingParenthesis;
+  }
+  if (Right.is(TT_TemplateCloser))
     return false;
   if (Right.is(tok::r_square) && Right.MatchingParen &&
       Right.MatchingParen->is(TT_LambdaLSquare))

unittests/Format/FormatTest.cpp

@@ -8757,6 +8757,7 @@ TEST_F(FormatTest, ParsesConfigurationBools) {
   CHECK_PARSE_BOOL(BreakStringLiterals);
   CHECK_PARSE_BOOL(BreakBeforeInheritanceComma)
   CHECK_PARSE_BOOL(ConstructorInitializerAllOnOneLineOrOnePerLine);
+  CHECK_PARSE_BOOL(DanglingParenthesis);
   CHECK_PARSE_BOOL(DerivePointerAlignment);
   CHECK_PARSE_BOOL_FIELD(DerivePointerAlignment, "DerivePointerBinding");
   CHECK_PARSE_BOOL(DisableFormat);